Polypropylene and polymeric vinylidene chloride ("VDC") may be combined to form sheets or films of clear, flexible plastic. The polypropylene and VDC are co-extruded together. The VDC has a relatively low gas permeability and forms a barrier to oxygen. Polypropylene and VDC film is commonly used to wrap and display food products such as cheese and meat. The film provides a seal about the food to assure a longer shelf life of the product. In addition, the film is transparent so that a prospective customer may view the enclosed product.
In the production of polypropylene-VDC film, large quantities of mill scraps of the film are generated as waste. The mill scraps present a disposal problem because the VDC layer is not easily separable from the polypropylene layer. The mill scraps cannot be recycled unless the polypropylene can be separated from the VDC. The mill scraps also cannot be placed in a landfill since the plastic material is non-biodegradable. Typically, mill scraps of polypropylene-VDC material are stored in warehouses because no satisfactory method exists for separating the polypropylene and the VDC.
In addition, VDC is used with other polymers besides polypropylene. For example, VDC can be used as the core layer of a multilayer packaging film. The outer layers of the film contain a polymer such as high-density polyethylene (HDPE). Also, VDC is used as a barrier layer in rigid containers for food packaging. For example, VDC forms an inner barrier layer, with the outer layers being formed of polypropylene, polystyrene, high-impact polystyrene (HIPS), or some other polymer with good mechanical properties, but poor barrier properties. Such rigid sheets are co-extruded.
Therefore, there exists a need for a method of efficiently separating VDC from other polymers so that the polymers may be recycled.